B Complex with C By 21st Century Overview & Drug Interactions

Niacin, also known as vitamin B3, is a water-soluble vitamin found in a variety of foods, including meat, poultry, fish, and fortified grains. It plays a variety of roles in the body, including in the metabolism of carbohydrates, fats, and proteins. It is also necessary for the production of energy in the body and in the synthesis of different hormones. Niacin deficiency is rare in developed countries, however, supplementation has been shown to have several positive benefits. For example, it can reduce the risk of diabetic neuropathy (i.e., nerve pain) and has been shown effective for treating some types of high cholesterol (extended-release niacin is used as a prescription drug in the United States for this purpose). There is a multitude of niacin forms available as dietary supplements, including NADH, niacinamide, and nicotinamide riboside, all with different properties.

Calcium is a vital nutrient found in various foods such as dairy products, certain vegetables, and many fortified items. Over 99% of the body's calcium is stored in the bones and teeth, predominantly as hydroxyapatite. The remaining calcium circulates in the blood, extracellular fluid, muscles, and other tissues, where it is essential for processes like nerve signaling, muscle contraction, vascular activities, glandular secretion, and maintaining cell membrane and capillary permeability. It also plays critical roles in enzyme reactions, respiration, kidney function, and blood clotting, and is involved in neurotransmitter and hormone release, amino acid uptake, vitamin B12 absorption, and gastrin secretion. Calcium balance changes with age: it is positive during periods of growth, stable in adulthood, and tends to become negative in older age. Calcium loss occurs through feces, urine, sweat, and shedding skin cells. In women, reduced estrogen levels decrease calcium absorption and retention, increase bone turnover, and lead to lower bone mass. Calcium supplements come in various forms, including citrate and carbonate, which differ mainly in their calcium content and absorption rates. Calcium citrate is easily absorbed and can be taken without food, making it suitable for older adults or those with low stomach acid. In contrast, calcium carbonate, which contains a higher percentage of calcium, is best absorbed when taken with meals.